578 TRANSACTIONS OF SECTION H 
ignorance. Moreover, we are able to command a vast army of newly discovered 
facts and attack the difficulties at issue in ways that were not open to those who 
went before us. 
in these circumstances it seems to me that I may perform a useful service 
by setting forth the views which my studies—both of the facts of Nature and 
ot the writings of contemporary biologists—have led me to adopt concerning 
Man’s genealogy, from the remote period when his ancestral line branched off 
from those of the other mammalian orders, and to make the attempt to appreciate 
the nature of the factors that determined each upward step in his march toward 
the supreme position among intelligent beings. 
In spite of all the precise knowledge, not only of the structure and functions, 
but even of the ‘ blood relationships,’ using that term in its literal as well as its 
metaphorical sense, of the Apes and Men, it is surprising that there should be so 
little agreement among leading authorities as to the precise line of Man’s 
ancestry. Biologists do not seem to be exempt from that spirit of unrest which 
is abroad at the present time; and there seems to be a strange reluctance to admit 
the obvious. Some zoologists try to persuade us that Man is not nearly related 
to the Old-World Apes, and seek for closer affinities with the New-World Apes, 
or even the Lemurs; others, again, exclude the Lemurs altogether from the Order 
Primates, or, on the other hand, would eliminate the Platyrrhine Monkeys from 
Man’s genealogy ; yet others claim a diphyletic origin for Man from the Apes. I 
do not propose to enter into the discussion of these problems * here, but rather, 
taking tor granted the genealogical line which 1, in agreement with many zoolo- 
gists, believe to be a close approximation to the real line of descent,® attempt to 
und an explanation of how each of the more significant advances was brought 
about in the course of Man’s evolution. 
‘his theme, in one form or another, has often formed the subject of Presi- 
dential Addresses before this Section. The last time the Association met in 
Scotland the late Professor Cunningham, whose death since then we all so deeply 
deplore, presided over this Section, and dealt with’ certain highly technical 
aspects of the subject in his own characteristically lucid manner. ut though 
only eleven years have elapsed since then, the additions to our knowledge of 
comparative anatomy, especially that relating te the brain, have been so great 
and so fundamental that we can regard the problems discussed by him from a 
very different and, I think, more intimate and instructive point of view. 
We no longer look, as he did, to that small patch of cortex in the left cerebral 
hemisphere, which has long been supposed to be the storehouse of the motor 
memories of articulate speech, as being the likeliest region to supply the key to 
the secret of Man’s mental pre-eminence. Since Pierre Marie* expressed his 
disbelief in any such so-called motor speech-centre, many physiologists and 
physicians have become sceptical as to the ability of the left inferior frontal 
convolution to control the mere muscular movements that produce speech. But 
even if we grant the basal contention upon which Professor Cunningham’s argu- 
ment was founded (as I think we are justified in doing, in spite of the writings 
of Marie and his followers), we cannot be said to explain the evolution of the 
modern steamship when we describe the steering-wheel which directs its course. 
Speech is a manifestation of the intelligence that depends upon the activity 
and co-operation of most parts of a large and highly organised cerebral cortex, 
acting as a whole; and what we have to discover is not so much how a particular 
series of groups of muscles bring about the mere motor acts of phonation and 
articulation, but what is the nature of the living mechanism which enables the 
mind to appreciate the multiplicity of sounds and other sensations, and to record 
such sensation-factors so that they may be recalled in memory and brought into 
relation as percepts with other sensation-factors in conscious experience, and 
made use of as guides to the realisation of the nature of causes and effects in the 
° A critical examination of some of these views will be found in Prof. Sollas’ 
Presidential Address to the Geological Society of London, February 1910. 
* The simian stages of this genealogy are admirably expressed in a diagram: 
made by Prof. Arthur Keith for his Hunterian Lectures ‘On Certain Phases in 
the Evolution of Man,’ Brit. Med. Journ., April 6, 1912, p. 788. 
’ Brit. Assoc, Report, 1901, p. 776. 
* *‘T’Aphasie,’ Semaine Médicale, 1906, p. 241. 
